Multirevolution electrical control system



Jan. 22, 1946. N. YARDENY 2,393,492

MULTIREVOLUTION ELECTRICAL CONTROL SYSTEM Filed Sept. 27, 1944 4 Sheets-Sheet 2 a I H 5! Y V 12 p36 f Efj M/CHEL M XHRDENY I INVENTOR ATTORN EY 1946- M. N. YARDENY 2,393,492

MULTIREVOLUTIONELECTRICAL CONTROL SYSTEM Filed Sept. 27, 1944 4 Sheets-Sheet 4 Fl G27 m MCHELMIQRDENX INVENTOR ATTORNEY L Patented Jan. 22, 1946 MULTIREVOLUTION ELECTRICAL. CONTROL SYSTEM Michel N. Yardeny, New York, N. Y.

Application September 27, 1944, Serial No. 555,950

18 Claims.

The invention relates to improvements in control apparatus and particularly to improvements in control apparatus for power drive placement of a useful load or object as by an electric motor, in a predetermined position or in one of several predetermined positions. I I

One of the features of the invention is the provision of means for moving the useful load through a cycle of movement, for example through one complete revolution, or through a predetermined number of cycles of movement, for example through a predetermined number of revolutions.

Another of the features of the invention is the provision of means to move the useful load through a predetermined fraction of a complete cycle of movement, for example through 'a predetermined angular fraction of acomplete revolution.

Another of the features of the invention is the provision of means to move the useful load through a predetermined number of complete cycles of movement and also through a fraction of a complete movement.

Another of the features of the invention is the provision of means for stopping the drive means when the useful load reaches the predetermined position and to provide means for suppressing hunting or oscillations of the system due for instance to inertia after the useful load has reached the predetermined position.

Another of the features of the invention is the provision of means for slowing up the movement of the drive means operating the useful load when the useful load approaches its predetermined position thereby facilitating positioning of the load.

Another of the features of the invention is the provision of means for adjusting the number of complete cycles of movement or the fraction of a complete cycle of movement through which the useful load is to be moved.

Other and further features of the invention will appear hereinafter and in the appended claims.

This application is a continuation in part of my copending application, Serial #490,767, filed June 14, 1943.

The invention is more fully explained in this specification when taken in connection with the accompanying drawings which illustrate by way of example, a now preferred embodiment of the invention.

Fig. 1 is a diagrammatic view of a control apparatus according to the invention employing after each reversal;

Fig. 4 is a similar view showing a modified beam-type relay with resistors for retarding the drive means after each reversal, and delayed action relays cooperating with the beam type relays;

Fig. 5 is a diagrammatic view of the arm of beam-type relay such as shown in Fig. 2 with its armature in flexed condition when its arms are attracted;

Fig. 6 is a detail view of control elements showing a raised gap between two conducting segments with a contact member bridging the gap;

Fig. 7 is a plan view of a structural design of a control apparatus according to the invention, with the top cover plate removed, and certain parts shown in a section as taken on line 1-1 of Fig. 8, and

Fig. 8 is a sectional view of the same, taken on line 8-8 of Fig. 7.

The control apparatus according to Fig. 1 shows two position selectors each'comprising two coacting units I, II; I, 11', etc. The number of the selectors corresponds to the number of different predetermined positions in which a useful load 2 may be placed, only two selectors being shown for the sake of clearness. Units II, II serve to control the number of revolutions, half revolutions or other desired characteristic cycles of movement of the useful load, while units I, I serve to control the accurate positioning of the useful load within the last revolution, half revolution or other cycle of movement of the useful load. Each of the units I, I, also, comprises a pair of control elements. One of these control elements is a contact arm H or i2, while the a other is composed of two metal segments or conducting members 3, l or 5, 8 separated by a gap or 7 associated with said arm, the segments are bridged by the arm. The contact arms are mounted on a common shaft I3 which is also arranged to operate the useful load 2 and connected by suitable step-down gears I4, I 8 and a shaft 82 to the armature I6 of a reversible electric motor, generally designated I1.

The motor circuit is controlled by two relay coils I8 and I8, one for each direction of rotation. The outer ends of the coils are connected by leads 28, 2| and switches 22, 28 with the segments 3, 4' and by leads 24, 25 and. switches 28, 21 with the segments 8, 8. The contact arms II, I2 are connected by leads 28, 28 to a terminal 38 of a source of current 3|.

Each of the units II, II also comprises one pair of control elements. One element includes a metal ring 32 or 33 with a projection 34 or 38 mounted on an insulation disc 88 or 81. The other control element includes a contact arm 38 or 31, these arms being mounted on a common shaft 38. The contact arms do not engage the rings 32, 33 themselves but are arranged to engage the points or projections 34, 38 only. The ring 32 is connected by a lead 38 and a switch 48 to a lead 4| extending from thejoined ends of the relay coils I8, I8, and ring 33 is connected by a lead 42 and a switch 43 to the common lead 4|. The contact arm 38 is connected by a lead 44 and a switch 48 to a lead 48 extending to the other terminal 41 of the source of current 3|. The arm 31 is connected by a lead 48 and a switch 48 to the lead 48.

Switches 28, 21, 43, 48 are mechanically connected by a common rod 88 operated by a handie 88 and switches 22, 23, 48, 48 are mechanically connected by a common rod 81 operated by a handle 88.

The two sets of switches may be mechanically coupled so that the closing of one set of switches will cause an opening of the other set of switches. Such coupling means are well known in the art and need not be described here in detail. It should also be understood that instead of switches operated by rods and handles, rotary type switches or any other suitable type of switches may be used.

Switches 48', 48' may be included in the leads 28, 48 for disconnecting the apparatus when not in use.

As it is apparent from the drawing, each of the relay coils l8, I8 is connected in series with the two pairs of control elements of unit I, I or II, 11, depending on which set of switches 22, 23,

28, 27 and 48, 55, 43, 48 is closed. The shafts I 3, 38 with the contact arms of the respective units are operatively connected together by gears 50, and an idler gear 52. The ratio of these gears is such that the relative angular position of the two shafts slightly changes with every revolution. If, for instance, the gear 58 is smaller than the gear 5|, having, for example, 55 teeth while the gear 5| has 56 teeth, then the relative angular position of the arms I2, 31 will be changed by a small angle a corresponding to 55/56 of 360 after every revolution. In the zero position the arms I2, 31 for instance, may be in the same angular position. Then after several revolutions the arms I2, 31 will be relatively displaced by a relatively large angle a, the arm I2 having advanced relative to arm 31. The angle a will determine the number of revolutions necessary for bringing the two arms back into the zero position and hence into the same relative angular position as before.

The discs 8, I8 of units 1, I and the discs 88, 81 of units II, 11' may be made in the form of gears connected together by idler pinions 88, 88; these disks, concentric with shafts I3 and 38 but not fixed to said shafts, are suitably mounted for rotational adJustment. The ratio between the gear discs 8, 88 and I8, I]. is preferably the same as the ratio between the gears 88 and 8 I.

Manually or otherwise operable pinions 88, 8| are provided, engaging the gear discs 88, 81 for the adjustment of the discs to new positions. It is of course also possible to provide friction or other means to set the arms for different predetermined positions.

For controlling the motor circuit, each relay coil I8, I8 has three contact arms, the relays being of a conventional triple pole, double throw type. The coil I8 operates arms 82, 83, 2 and the coil I8 operates arms 84, 88, III. The arm 82 normally engages a contact point 88 connected by a lead 81 to the lead 48. The arm 83 normally engages a contact point 88 connected by leads 88 and 12 to one end of a reversing field winding I8 of the motor ll. When attracted by the coil I8, the arm 83 engages a contact point 1| connected by lead 12 with the same winding In thus causing rotation of the motor in one direction. The contact arm 84 of the relay coil I8 normally engages a contact point 13 connected by a lead 14 with the arm 82 of relay I8 and is connected by a lead 18 with the lead 48. When attracted arms 82 and 84 engage blind points 83', the arm 85 is connected by a lead 18 with the arm 82 of relay I8 and normally engages a contact point I1 connected by a lead I8 with the lead 48. When attracted by the coil I8, the arm 85 engages a point 1.8 connected by a lead 88 with one end of the second reversing field winding 8| thus causing a rotation of the motor in the opposite direction. The relay arms 2 and 2 I 5 are connected together by a lead 2 I 8 and normally engaged contact points 2|1, 2| 8 connected by a common lead 2I8 to one end of relay coil I8. The arms 2|4, 2I8 when attracted by the relay coils, engage contact points 2|2, 2| 3, connected by a common lead 2l|l to the coil I8 through a resistor 2| I.

The common lead 4| of the relay coils is connected by a lead 34 and a resistor 84' with the Joined ends of the motor windings III, 8|. The resistance of resistor 84 is selected so that the current through the resistor will be insuiilcient,

to energize the coils I8 or I8 to a point where they can attract their arms, but will maintain otherwise energized coils sufllciently magnetized to retain their arms raised after they have been attracted. When the arms of both relays I8, I8 are attracted the motor will be caused to stop, the arms 82, 64 then resting against blind points 83.

The joined ends of the field windings 18, 8| are also connected to one terminal of the armature I8 by a lead 82, the other armature terminal being connected by leads I88, 88 to the terminal 38 of the source of current 3| through a. speed reducing governor generally designated 8|,

-mounted preferably on a shaft extension 82' of the motor Il. It is of course also possible to couple the governor 8| through gears t the motor. The governor 8| serves to facilitate stopping of the motor when one of the gaps is bridged by the corresponding energized contact arm and to prevent hunting of the motor back and forth caused by inertia in the system. The governor comprises a spring 83 connected with a collector ring 04 and normally engaging a contact point connected with a collector ring 00. The rings l4, 00 are engaged by contact brushes 01, 00 thus connecting the leads 03, I00 which in turn connect the armature to terminal 30. The governor can be bypassed by leads I00, IOI connected with two pairs of spring contacts I02, I03, and I04, I 00 of a reversing switch. The spring contacts tend to urge their contacts into a disengaged position. A finger I00-supported on a collar I01, frictionally mounted on the shaft extension 02' normally rests against one of two stops I00, I00, depending on the direction of the m0- tor rotation and closes one of the pairs of contacts I02, I03 or I04, I05 during a'short period aftereach reversal of the motor rotation. However, while the flnger I00 moves from one stop to the other, both pair of spring contacts I 02,

I03 or I04, I00 are disconnected or opened. The by-pass through leads I00, IN is now interrupted and the governor is connected in series with the armature II of the motor by leads I00, 03. If during this short period the motor speed exceeds a predetermined value, spring 93 will leave point 00 due to the centrifugal force thus interrupting the motor circuit until the centrifugal force has suillciently decreased by the reduction of the motor speed to permit a return of spring 03 into its position engaging point 30. This reduction of the motor speed caused by the repeated fluctuation of the motor current will prevent a repeated overrunning of a gap, such as 0, by a contact arm such as I2.

A lead IIO including a switch 0' may be provided for permanently short circuiting the governor if desired.

Apparatus as shown in Fig. 1 may be conveniently used for operating a device, such as a core of a radio tuning coil as, for instance, by means of a screw (not shown) rotated by the load shaft I3 of \the device. The selector units I-II, I-1I',

etc., are set for such and other purposes by means of the manually operated pinions 60, Si in positions corresponding to the desired positions of the core, requiring a predetermined number of revolutions of the load shaft I3. Hence each selector, when energized, will cause the shaft I3 to make as many revolutions plus such a fraction of a revolution as are necessary to bring the core into the particular predetermined position. The number of the revolutions of the shaft I3 before reaching a new position is of course different and depends on the prior position of the core.

Assume, for instance, that the core shall have two predetermined positions, one say at a zero distance from the starting point, and the other at a distance of a fraction of an inch, and that the screw, operated by the shaft I3, must make for instance, twenty revolutions and for p acing the core in the second position. The selectors are then preset as follows: Assuming the first selectors, I-II controlling the zero position of the core, are in their stopping positions of the core, are in their stopping positions as shown in Fig. l, with the arms II, 36 parallel to each other, for example, and engaging the gap 1 and projection respectively, and further assuming that the gap 0 and projection 35 were originally in the same positions as shown for gap I and projection 34, that is, in positions in which they would be engaged by the arms I2 and 3'! respectively, then the selectors I, II are set for the desired new position of the load by rotating the discs of the selector I'-II' in the direction of the operating movement so as to cause the shaft "to make twenty full revolutions and 00 (for instance, to the left in Fig. 1), thereby causing the gap 0 and projection 30 to be placed in the position shown in Fig. l. The positions of selector units I and II are not affected by such setting of units 1 and II. After twenty full revolutions of the disc I0 (or forty half revolutions), by hand, the gap 0 is returned to its original position. By adding a fractional revolution of 60, the gap 0 will be displaced to the left, approximately as shown in Fig. l, the angle b being equal to the additional 60. The projection 30, however, will be lagging behind with each revolution of the disc 01 by the small angle 0', representing 360 55/56 of .one revolution, and at the end of twenty revolutions will lag by the large angle a, representing the sum total of the angles a for twenty revolutions of the disc I0.

Other sets of discs, ii any, will be similarly preset.

In theposition of the selectors shown in Fig. l, the load is in its zero or starting position, corresponding to the stopping position of the selector I-1I. If it is desired to place the load in the next position, corresponding to the settin of selectors I'-II, the switches 22, 23, and 00. 03 are opened and switches 20, 21, 43, 49 are closed (with the switches 40', I! closed). Both the relays are now deenergized. Since the arm 31 does not touch the projection 30, the motor will always start rotation in a certain direction determined by the connections to the relay arms,

I for example, in a clockwise direction; the motor will move arms I2 and 31, in this direction, away from gap 0 and projection 35 or, in other words, in this case in the wrong direction. But this is to be corrected, in the manner now to be described.

The motor current will flow from the terminal 30 and switch 40' through the leads 83, I0 I, closed contact points I03, I02, or closed contacts 33, of the governor 9i, lead I00, armature I8, winding 10, lead 12, point 08, arm 63, point 13, arm 84, and leads I5, 06 to the switch 49' and terminal 41. The relay coils will remain deenergized their circuits being disconnected at the arm 31 until this arm reaches the projection 35. A small current will pass, however, from the lead lI through the lead 0| and resistor 84' while the motor circuit is closed, but this current will be insufllcient to cause the relay coils to attract the arms 62, 63, 04, 05, 2M and 2I5. The motor will continue its rotation in the same direction until the contact arm 31 touches for the first time the projection 30. The arm l2 at that moment will engage the segment 8 due to the previously explained setting of this arm thus momentarily energizing the relay coil I 9, the circuit of which will be closed from the terminal 30 and switch 48' through the lead 20, arm I2, segment 0, lead 25, switch 21, coil I9, leads II, 42, switch 03, ring 33, projection 3!, arm 31, lead 48, switch 49, lead 46, switch 49' and terminal 41. The relay arms 64, 65, N5 will be attracted, closing the motor circuit as follows: From the terminal 30 and switch 48', through the leads 83, I 0|, contact points I03,

I02, lead I00, armature I8, winding 8i, lead 80,

point 19. arms 85, 62, point 86, leads 81, 46 to the switch 49' and terminal 41. The ,direction' of the motor rotation will he therefore reversed so as to cause the arm I2 to move towards the gap 0 and the arm 31 to move towards the projection 35. The arms 04, 00, H5, once attracted by the relay coil I0, will remain so attracted; the

current through the resistor 04' being sufficient to energize the coils for retaining the already attracted arms. The arms of the relay I3 will also remain attracted when the arms I2 moves from segment 6 to segment 5, because sufficient current will still flow through the relay I3 to retain the raised arms, a connection now being established between segments 5 and 6 through the lead 24, switch 26, lead 2), resistor 2, point 2I3, raised arm 2I5, lead 2I5, arm 2, point 2H, and lead 2I9 to the lead 25, ,switch 21 and segment 6, the resistances of resistors 34 and 2H being selected so that with one or both resistors in series, the relay coils cannot attract the arms but are still effective to retain the already attracted arms.

Because of the angular difference a between the gap 8 and the projection 35, the relay I8 will remain deenergized when the arm I2 passes the gap 8, since this gap during the first revolutions of the shaft I3 will be bridged by the arm I2 only when the arm 31 is disengaged from the projection 35. With each revolution of the shaft I 3, however, the arm 31 will lag by the angle a behind the arm I2, and at the end of twenty revolutions (or 40 half revolutions) the total lag will be equal to the angle a. The arm 31 will then engage the projection 35. The arm I2 will continue its rotation only until it bridges the gap 8 when both the relay cOlls will be simultaneously energized, attracting all six relay arms and disconnecting the motor circuit. The width of the projection 35 is sufllcient to remain in engagement with the contact arm 31 if the arm I2 slightly overruns the gap 8 by inertia. This will energize the other relay I8, and cause the arm I2 to return into the gap. As soon as the arm I2 bridges the gap, both relays are energized, attracting both arms 214, 2I5 thereby interrupting the motor current and breaking the connection between the segments 5, 6. When the arm I2 engages for a moment the segment} leaving seg ment 6, relay I9 will be deenergizd and its arms 64, 65, 2I5 will be released, because the current through the retaining resistors 34', 2| I was interrupted when both relays were energized. The motor will be now reversed, as was explained above. As previously explained the governor will become operative at the moment of the reversal of the motor rotation thereby reducing the motor, thus permitting arm I2 to settle in the gap 8.

The arms II and 36 of units I and II will be then moved to new positions, with a lag of twenty revolutions and 60 between them. If the switches 26, 21, 43, 49 are now opened and switches 22, 23, 40, -45 closed the motor will rotate in the opposite, or clockwise direction for bringing the arms I I, 36 back to the zero position as shown in Fig. 1.

If the gap 3 is initially placed to the right of the arm I2 and the point 35 to the right of the arm 31, the motor starts always in the clockwise direction and moves in the right direction from the beginning, then no corrective of the motor rotation will be required.

It is understood that any suitable mechanical, magnetic or electro-dynamic braking means may be provided for stopping the motor or the shaft I3 when the desired predetermined position is reached by the load. Similarly any suitable arrangement may be provided for preventing hunting or oscillations of the motor when the gap 3 is reached by the contact arm I2 and the projection 35 is at the same time engaged by the contact arm 31. Such antihunting arrangements are disclosed, for instance, in my D. 5. Patent No. 2,342,717 and may include raised end portions of the conducting members at the gap for a yieldable engagement by a ball-shaped point on the contact arm, an arrangement of this kind is illustrated in Fig. 6 as comprising a ball II' supported on arm II, raised end portions 3', 4' engaged by the ball.

The apparatus according to the invention can be used with diil'erent types of relays and with difl'erent types of the motors. One of such modiilcations is shown in Fig. 2 illustrating the use of a beam-type relay and of a shunt wound direct current motor. The selectors are the same as in Fig. l and the identical parts are denoted by the same numerals, including the relay coils I3 and I9. These coils operate a flexible contact beam comprising an armature having two contact arms I 20, III pivotally supported at I22. Springs I23 urge the arms to stay in a straight line, but will yield as shown in Fig. 5 when both the contact arms are simultaneously attracted by the magnet coils I8, I9. The arms have no intermediate position and always engage two of the contact points I24, I25, I26, I21. The mechanical construction of the arms I20, III is such that when relay coil I3 is energized, contact arm I20 engages contact point I24, while the contact arm I2I is urged by springs I23 against contact point I21. If now both relays I3 and I3 are energized, contact arm I20 will retain its position, but contact arm I2I will engage contact point I25. I! now relay coil I3 is deenergized, the contact arm I20 will be urged by spring I23 against contact point I 26, but contact arm III will engage as before contact I25. If now coil I3 is also deenergized, both arms I20 and I2I will remain unchanged in position, that is, respectively engaging contact points I26, I25. Thus for each possible position of contact arm I20, there are two possible positions of contact arm I2I; and vice versa. They also cannot remain in a deflected position engaging the points I24, I25 unless both the relay coils are energized. The contact arms I20 and I2I are insulated from each other for instance by insulation blocks 23, 29, and are connected (Fig. 2) by flexible leads I30, I3I to the armature I32 of a motor I33. The shunt winding I34 of the motor is connected by leads I35, I36 and a switch I31 to the leads 33, 43 respectively connected with terminals 30, 41 of the source of current 3|. The points I26, I21 are connected by leads I38, I33 to the lead 33.

A frictional sliding clutch I40 may be provided between the motor and the gear or pinion I4. Such a clutch acts to prevent hunting of the motor by absorbing its inertia by friction after each reversal of rotation of the motor. There are omitted from Fig. 2, the resistor 34' and its connections, the governor 9 I, the reversing switch, and the gears 58, 59 of Fig. 1. Discs 3 and I0 can be adjusted independently of discs 50, 51' by means of pinions 60', 6|.

Instead of a gear connection between the pinions and the discs, a friction drive may be provided. In order to adjust the discs of units I, II and I, II independently, gap 1 or 3 is first placed in a position according to the desired final angular position of shaft I3 by means of pinion 60' or 6|. Then disc 56 or 51 is turned by means of pinion 60 or 6I so that contact point 34 or 35 is placed in the same angular position as gap 1 or I. Thereupon, contact point 34 or 35 is displaced by an angle a corresponding to the desired total number of revolutions of shaft I3 and hence of hunting or oscillating. The connected resistor is' load 2. The displacement of the contact point 34 or 35 may be to the right or to the left corresponding to the desired direction of rotation.

It is also possible to adjust the contact arms rather than the discs.

Operation of the apparatus according to Fig. 2

always assume the position shown infull lines' in Fig. 2 when the coils are deenergized by opening all the switches simultaneously. Insteadof I or in addition to controlling the position of relay arms I20, I2I by providing relays having a different speed of operation, it is also possible tojpro vide means causing switches 23 or 21 to close before or after switches 22, 26 when switch rods 81 or 85 are operated. Such means may comprise for example an elongated contact element 225 for switch 22 and an elongated element 226 for switch 26, and a wider opening of the arms of switches 23, 21 than of the arms of switches 22, 26 as shown in Fig. 2. Then switch arms 22, 26 will disengage the corresponding elements 225, 226 after switch arms 23, 21 are disengaged.

If the switches 26, 21, 43, 49 are closed, as well as the switches 48', 49', both the relay coils will at first remain deenergized as was explained in connection with the operation of the device of Fig. 1. Assuming now the shunt field switch I31 to be closed, the motor I32 will be energized by the current flowing from the terminal 41 through the switch 49, lead 46, contact point I24, arm I20, flexible lead I30, armature I32, flexible lead I3I,

, arm I 2I, contact point I21, and leads I39 and 83 to the other terminal of the source of current 3|. The motor. will always start rotation in the same direction, which if the wrong one will be corrected as soon as the contact arm 31 touches the contact projection 35 for the first time as explained in connection with Fig. 1.

At the end of the operation, when the gap 8 is finally bridged by the contact arm I2 and both the coils I8, I9 are energized, both the arms I20, I2I will be attracted by the coils against the resistance of the springs I23 as shown in Fig. 5. The armature I32 will be short circuited through the lead 46 and will be more rapidly stopped by dynamic braking caused by the magnetic field of the shunt winding I34, this winding being energized aslong as switch I31 is closed.

Instead of providing a governor as shown in Fig. 1 for retarding the motor rotation after each reversal to suppress oscillations or hunting of the motor, the arrangement shown in Fig. 3 may be used in which resistors and dash'pots are employed.

According to Fig. 3 resistors I42, I43 connect points I 26, I21 with resilient contact members I44, I45, normally raised as shown at the left in Fig. 3, by the action of springs I44 and therefore are separated from points I26 and I21 respectively. Thus when the contact arm I20 or I2I .is moved downward, it first engages the raised end of the contact member I44 or I45, thereby closing the circuit for the motor through the resistor I42 or I43. The motor will therefore rotate slowly and can b -easily stopped without short circuited when the arm I20 or I2I finally presses resilient contact member I44 or I46 against the corresponding contact point I26 or I21. To increase the length of time during which a resistor is effective, dash pots I46, I41 may .be provided, with plungers I48, I49 connected by rods I50, I5I to the respective relay arms I20 and I2I. Valves I48, I49 in the plungers close by-pass openings in the plungers when the plungers are moved downward, thereby retarding their movement, and ar opened by the upward movement of the plungers, allowing the plungers to move rapidly upward.

Another similar arrangement using resistors and time delayed relays for retarding the motor rotation after reversal is shown in Fig. 4, in which resistors I52, I53 are included in the leads I38, I39 so that the motor circuit is first closed through one of these resistors when the arms I20, I2I engage the respective contact points I26, I21. In addition to engaging the points I26 and I21 arms I20 and I2I engage at the same time respective contact points. I54 or I55. Each of these points is connected to an end of one of the relay coils I60, I6I, the outer ends of which coils are connected by leads I62, I63 to the lead 46. The coils, when energized, attract contact arms I64, I65 connected with respective leads I66, I61, both connected by lead I39 to terminal 30. The arms I64, I 65 when attracted engage contact points I68, I69 connected with the points I26, I21, thereby short-circuiting or by-passing the resistors I52, I53, and restoring the normal rotational speed of the motor.

The relay coils I50, I6 I if desired may be of a according to the invention is illustrated in Figs.

7 and 8.

As here shown, selector discs 9, I0, 9, I0 are slidably and rotatably supported in horizontal slots I10 in posts I1I at one side and in slots I13 in an end post I14. The posts are suificiently broad so that each slot covers several teeth at the periphery of the discs. Guiding blocks I16 may be placed in the slots I13 and urged by springs I11 against the periphery of the discs so that the discs are held accurately in their intended positions in the slots by being pressed against the bottoms of slots I10. The posts I1I also have slotsl18 for discs 56, 51, 56', 51, An end post I is provided similar to the post I14 with slots I13 and guiding blocks I16 and springs I11. The toothed peripheries of the discs mesh with idler pinions 58, 59, 58, 59', rotating on a common shaft I8I, the ends of which ar held in end plates I82, I83. The posts I1I, I14, I80 are held between these end plates by screws I84,

threaded in holes I in the ends of the posts.

Additional corner posts I86 may be provided between the plates. The shafts I3 and 38 have the arms II, I2, II, I2 and 36, 31,36, 31' keyed thereon. The ends of the shafts I3 and 38 are journaled in recesses in the end plates I82, I83. The shaft 92 is connected to a motor (not shown), and the shaft I3 is connected to a useful load (not shown). The upper ends of the shafts I3 and 38 mount indicating dials I81, I88 with suitable divisions Or calibrations to indicate the position of the load relative to fixed indices I89, I90. The shafts I3 and 38 are connected together by gears 50, 5| 52 keyed to their respective shafts. The

ratio of the gears is selected according to the desired maximum number of revolutions of the useful load. Thus with the ratio 55/56 it will be possible to impart up to 25 revolutions to the useful load.

The gear 50 is also engaged by a pinion 19! on a shaft K52 extending above the upper end plate M2 and provided with a top knurled head !93 for its manual operation if it is desired manually to change the load position. A dished spring I94 (Fig. 8), for serving as a frictional clutch may be placed between the gear 50 and the worm gear l5. Gear is rotatably mounted on the shaft l3, while gear 50 is keyed to shaft l3. The clutch spring is selected for frictional resistance so that the worm gear [5 normally functions to drive the gear 56 and the shaft [3, but said spring slides relatively to the gear 50 and the shaft l3 when the gear 50 is manually rotated for manual positioning of the load connected to shaft iii, the ear it bein then held by the irreversible We drive it,

The discs El El, 58, 5'! are engaged by pinions bi, Gil", 6i" mounted on shafts H36, 191, 528, lSEl with top knurled heads 2% for their manual operation, when it is desired to reset the d cs to new positions.

The rings 32, (i3, 32, 33' are engaged by contact brushes 22E mounted on an insulation post 9) I and connected to leads 39, 42 etc. Contact blushes engage the peripheries of semi-am nuler extensions 284 connected to the segments etc. The segments 3, 5, etc, are shown as cormected by rivets 265 with rings 205 underneath the discs 8, i8, etc., engaged by contact brushe- The brushes Mi are connected to the leads it, it, etc, and the brushes are connected to the leads 2 l, 25, etc.

The width of the contact projections 34 must preferably be sufficient to allow for any possible backlash in the gears Ell, Si, 52. It should be noted that such a backlash does not affect the accuracy of the device since the final stopping position is determined by one of the contact arms ll, it, l2, l2 bridging the corresponding gap between the segments 3, l, 5, 6.

Control apparatus as shown in Figs. 7, 8 may be used in conjunction with a circuit such as illustrated in Fig. l or with any other suitable circuit and is Within the Scope of the invention.

As previously explained the load 2 is connected by any suitable means to shaft i3 and the motor or oth r drive means is connected to shaft 52. Shaft when rotated drives gear wheel l5 through gear Wheel i4. Gear 14 is frictionally coupled through spring 94 with gear keyed to shaft 3 so that a rotation of gear 50 causes shaft id to rotate and hence also the useful load and the contact arms H, H, [2, l2. The gear 50 also drives the gear 5! through gear 52, gear 5! being keyed to shaft 3 Gear 5i causes this shaft to rotate and with it the contact arms 36, 36, 31', 31" on shaft 38.

The discs 8, it, 9', ill and 32, 33, 32', 33' can be set by rotating the appropriate shaft I96, 191 by means of knurled heads 260.

If it is desired to rotate shaft l3 and hence the load manually, shaft 282 is rotated. The friction disc or gear disc l9| supported by shaft E52 will then rotate gear 50 by overcoming the friction coupling formed by spring I94, said gear being held stationary by the irreversible Worm vention above described or referred to may be utilized or substituted in other embodiments.

While the invention has been described in detail with respect to certain particular preferred examples, it will be understood by those skilled in the art after understanding the invention that various changes and further modification may be made and parts of the improvements may be used without others without departing from the spirit and scope of the invention, and, therefore, it is intended in the appended claims to cover all such changes and modifications.

I claim:

1. Control apparatus for placing a useful load in a predetermined position, comprising reversible drive means capable of making several cycles of movement for placing the useful load in the predetermined position; means for rendering the drive means operative; a pair of relatively movable control elements. one element comprising conducting means having a neutral point, the other element comprising a contact arm for engaging the conducting means; a second pair of relatively movable control elements, one element of the second pair comprising a contact point, the other element of the second pair comprising a contact arm for engaging the contact point, one movable element of each pair of control elements being arranged to be moved by the drive means through a range of more than one cycle of movement, transmission means between the two elements moved by the drive means, said transmission means being arranged to move the control elements at diiierent speeds for causing the control elements to be progressively displaced relative to each other; means to electrically control the direction of movement of the drive means by the position of the first contact arm at one or the other side of the neutral point; and means to stop the drive means in response to the first contact arm reaching the neutral point and the second contact arm simultaneously reaching the contact point as controlled by the progressively changed displacement between the contact arms, the original relative positions of the control elements determining the number of cycles of movement or fractions thereof required for bringing both contact arms in simultaneous engagement with the neutral point and the contact point respectively.

2. Control apparatus for placing a useful load in a predetermined position, comprising reversible drive means capable of making a plurality of revolutions for placing the useful load in the predetermined position; means for rendering the drive means operative; a pair of relatively rotatable control elements, one element comprising conducting means having a neutral point, the other element comprising a contact arm for engaging the conducting means; a second pair of relatively rotatable control elements, one element of the second pair comprising a contact point, the other element of the second pair comprising a contact arm for engaging the contact point, one rotatable element of each pair of control elements being arranged to be rotated by the drive means through a range of more than one revolution; transmission means between the two elements rotated by the drive means, said transmission means being arranged to rotate the control elements at different speed for causing the control elements to be progressively angularly displaced relative to each other; means to electrically control the direction of rotation of the drive means by the position of the first contact arm at one or the other side of the neutral point; and means to stop the drive means in response to the first contact arm reaching the neutral point and the second consimultaneously reaching the contact pointas controlled by the progressively changed angular displacement between the contact arms, the original relative positions of the control elements determining the number of revolutions or fractions thereof required for bringing both contact arms in simultaneous engagement with the neutral point and the contact point respectively.

3. Control apparatus for placing a useful load in a predetermined position, comprising reversible drive means capable of making several cycles of movement for placing the useful load in the predetermined position; a pair of relatively movable control elements, one element comprising conducting means having a neutral point, the other element comprising a contact arm for engaging the conducting means; a second pair of relatively movable control elements, one element of the second pair comprising a contact point, the other element of the second pair comprising a contact arm for engaging the contact point, one movable element of each pair of control elements being. arranged to be moved by the drive means through a range of more than one cycle of movement; transmission means between the two elements moved by the drive means, said transmission mean being arranged to move the control elements at different speed for causing the control elements to be progressively displaced relative to each other; means to electrically control the direction of movement of the drive means by the position of the first contact arm at one or the other side of the neutral point; means to stop the drive means in response to the first contact arm reaching the neutral point and the second contact arm simultaneously reaching the contact point; as controlled by the progressively changed displacement between the contact arms, the original relative position of the control elements determining the number of cycles of movement or fractions thereof required for bringing both contact arms in simultaneous engagement with the neutral point and the contact point respectively; means to start the movement of the drive means always in the same direction independent of the control elements; and means to connect the drive means for movement of the contact arms toward the neutral point and the contact point respectively in response to the second contact arm reaching the contact point for the first time.

4. Control apparatus for placing a useful load in a predetermined position, comprising reversible drive means capable of making several cycles of movement for placing the useful load in the predetermined position; a pair of relatively movable control elements, one element comprising conducting means having a neutral point, the other element comprising a contact arm for engaging the conducting means; asecond pair of relatively movable control elements, one element of the second pair comprising a contact point, the other element of the second pair comprising a contact arm for engaging the contact point, one movable element of each pair 01 control elements being arranged to be moved by the drive means through a range of more than one cycle of movement; transmission means between the two elements moved by the drive means, said transmission means being arranged to move the control elements at different speed for causing the control elements to be progressively displaced relative to each other;

means to electrically control the direction of movement of the drive means by the position of the first contact arm at one or the other side oi taneously reaching the contact point as controlled by the progressively changed displacement between the contact arms, the original relativ position of the control elements determining the number of cycles of movement or fractions thereof required ior bringing both contact arms in simultaneous engagement with the neutral point and the contact point respectively; means to start the movement or the drive means always in the same direction independent of the control elements; means to connect the drive means for movement of the contact arms toward the neutral point and the contact point respectively in response to the second contact arm reaching the contact point for the first time; and means for maintaining said last mentioned direction of rotation of the drive means until the drive means are stopped.

5. Control apparatus as described in claim 1 in combination with means for adjusting the positions of controlelements operated otherwise than by the drive means.

6. Control apparatus as described in claim 1 in combination with means for adjusting the positions of control elements operated otherwise than by the drive means independently oi'each other.

7. Control elements as described in claim 1 in combination with yieldable means for connecting the drive means with the control elements; and manual means operable independently oi! the drive means for adjusting the control elements operated by the drive means.

8. Control apparatus as described in claim 1 in combination with means to retard the movements of the drive means in response to the drive means approaching the position in which they are stopped. v

9. Control apparatus for placing a useful load in a predetermined position, comprising reversible drive means capable of making several cycles oi movement for placing the useful load in the pre determined position; means for rendering the drive means operative; a pair of relatively movable control elements, one element comprising conducting means having a neutral point, the

other element comprising a contact arm for engaging the conducting means; a second pair of relatively movable control elements, one element of the second pair comprising a contact point,

the other element of the second pair comprising a contact arm for engaging the contact point, one movable element of each pair of control elements being arranged to be moved by the drive means through a range of more than one cycle of movement; transmission means between the two elements moved by the drive means, said transmission means being arranged to move the control elements at diflerent speed for causing the control elements to be progressively displaced relative to each other; relay means for electrically controlling the direction of movement of the drive means and for stopping the drive means in response to the first contact arm reaching the neutral point and the second contact arm simultaneously reaching the contact point, as controlled by the progressively charged displacement between the contact arms, the original relative position oi the control elements determining the number of cycles of movement or fractions thereof required for bringing both contact arms in simultaneous engagement with the neutral point and the contact point respectively.

10. Control apparatus for placinga useful load in a predetermined position, comprising reversible drive means capable of making several cycles of movement for placing the useful load in the predetermined position; means for rendering the drive means operative; a plurality of selectors, each selector comprising a first and a second pair of relatively movable control elements, one element of each first pair comprising conducting means having a neutral point, the other element of each first pair comprising a contact arm for engaging the corresponding conducting means, each second pair comprising one element having a contact point, the other element of each second pair comprising a contact arm for engaging the corresponding contact point; one movable element of each first and second pair of control elements being arranged to be moved by the drive means through a range of more than one cycle of movement; transmission means coupling the two elements moved by the drive means, said transmission means being arranged to move the coupled control elements of each pair at different speed for causing the said control elements to be progressively displaced relative to each other; means for selectively energizing one of said selectors; means to electrically control the direction of movement of the drive means by the position of the first contact arm of the selected selector at one or the other side of the neutral point; and means to stop the drive means in response to the first contact arm of the selected selector reaching the corresponding neutral point and the second contact arm of the selected selector simultaneously reaching the corresponding contact point, as controlled by the progressively changed displacement between the control elements, the original relative positions of the control elements of the selected selector determining the number of cycles of movement or fractions thereof required for bringing both contact arms of the selected selector in simultaneous engagement with the corresponding neutral point and the corresponding contact point respectively.

11. Control apparatus for placing a useful load in a predetermined position, comprising reversible drive means capable of making several revolutions for placing the useful load in the predetermined position; means for rendering the drive means operative; a plurality of selectors, each selector comprising a first and a second pair of relatively movable control elements, one element of each first pair comprising conducting members separated by a gap, the other element of each first pair comprising a rotary contact arm for engaging the corresponding conducting members and arranged to bridge the corresponding gap, each second pair comprising one element having a contact point, the other element of each second pair comprising a rotary contact arm for engaging the corresponding contact point; the rotary contact arm of each first and second pair of control elements being arranged to be rotated by the drive means through a range of more than one revolution; transmission means coupling the two contact arms of each pair, said transmission means being arranged to move the coupled contact arms at different relative speed for causing the said contact arms to be progressively displaced relative to each other; means for selectively energizing one of said selectors; means to electrically control the direction of rotation of the drive means by the position of the first contact arm of the selected selector at one or the other side of the gap; and means to stop the drive means in response to the first contact arm of the selected selector bridging the corresponding gap and the second contact arm of the selected selector simultaneously reaching the corresponding contact point, as controlled by the progressively changed displacement between the contact arms, the original relative positions of the contact arms of the selected selector determining the number of revolutions or fractions thereof required for bringing both contact arms of the selected selector in simultaneous engagement with the corresponding gap and the corresponding contact point respectively.

12. Control apparatus for placing a useful load in a predetermined position, comprising a reversible motor capable of placing the useful load in the predetermined position; a plurality of selectors, each selector comprising a first and a second pair of relatively movable control elements, one element of each pair comprising conducting members separated by a gap, the other element of each pair comprising a contact arm for engaging the corresponding conducting members and arranged to bridge the gap, each second pair comprising one element having a contact point, the other element of each second pair comprising a contact arm for engaging the corresponding contact point, one movable element of each first and second pair of control elements being arranged to be rotated by the motor through a range of more than one revolution; transmission means coupling the two elements of each pair rotated by the drive means, said transmission means being arranged to rotate the coupled control elements at different relative speed for causing the said control elements to be progressively displaced relative to each other; means for starting the motor; means for selectively energizing one of the selectors; relay means having two coils for controlling the direction of rotation of the motor in response to one coil being energized and for stopping the motor in response to both coils being energized; and means to energize one of the coils by the first contact arm of the selected selector engaging the corresponding conducting members at one or the other side of the corresponding gap and the second contact arm of the selected selector simultaneously reaching the corresponding contact point and to energize both relay coils by the first contact arm of the selected selector reaching the corresponding gap and the second contact arm of the selected selector simultaneously reaching the corresponding contact point, as controlled by the progressively changed displacement between the contact arms, the original relative positions of the contact arms of the selected selector determining the number of the revolutions or fractions thereof required for bringing both contact arms of the selected selector in simultaneous engagement with the corresponding gap and the corresponding contact point respectively.

13. A control apparatus as described in claim 12 in combination with means for maintaining the direction of rotation of the motor as established by energizing one of the relay coils, independent of the positions of the contact arms of the selected selector until the said contact arms reach their positions for stopping the motor.

14. Control apparatus for placing a useful load in a predetermined position, comprising reversible drive means capable of making several revolutions for placing the useful load in the predetermined position; a plurality of selectors, each selector comprising a first and a second pair of relatively movable control elements, one'element of each pair comprising conducting members sepby the drive means through a range of more than one revolution; transmission means coupling the two movable elements of each pair rotated b the drive means, said transmission means being arranged to rotate the coupled movable control, elements at different relative speed for causing the said control elements to be progressively displaced relative to each other; means for starting the drive means independent of the control elements; relay means having two coils and switch arms for controlling the direction of rotation of the drive means in response to one coil being energized and {or stopping the drive means in response to both coils being energized; means to energize momentarily one 01' the coils by the first contact arm of the selected selector engaging the corresponding conducting members at one or the other side of the corresponding gap and the second contact arm of the selected selector simultaneously reaching the corresponding contact point the energized relay coil thereby attracting the corresponding switch arms; and means to retain the switch arms attracted independent of the relative positions oi. the control elements of selected selector, said energizing means being further energized to energize both relay coils by the first contact arm of the selected selector reaching the corresponding gap and the second contact arm of the selected selector simultaneously reaching the corresponding contact point, as controlled by the progressively changed displacement between the contact arms, the original relative positions of the contact arms of the selected selector determining the number of the revolutions or fractions thereof required for bringing both contact arms of the selected selector in simultaneous engagement with the corresponding gap and the corresponding contact point respectively,

15. A control apparatus as described in claim 14 in which said retaining means comprises impedance means included in connections between the relay coils and a source of'current.

16. A control apparatus as described in claim 12 in which said relay means comprises a beamtype switch arm composed of two members yieldably joined together for simultaneous undeflected movement under attraction of one of the relay coils for rendering the motor operative, and arranged to be deflected in the same direction in response to both relay coils being energized for stopping the motor. I

1'7. A control apparatus as described in claim 12 in which said relay means comprises a beamtype switch arm composed of two members yieldably joined together for simultaneous ,undeflected movement under the attraction of one or the relay coils for rendering the motor operative, and arranged to be deflected in the same direction in response to both relay coils being energized for stopping the motor; impedance means; and means to include the impedance means in the motor connections in response to and during the undeflected movements or the switch arm.

18. A control apparatus as described in claim 12 in which said relay means comprises a beamtype switch arm composed of two members yieldably Joined together for simultaneous undeflected movement under the attraction of one of the rela coils for rendering the motor operative, and arranged to be deflected in the same direction in response to both relay coils being energized for stopping the motor; impedance means; means to include the impedance means in the motor connections in response to and during the undeflected movements of the switch arm; and means to retard the undeflected movements 01' the switch arm.

MICHEL N. YARDENY. 

